The audio system is disabled when it is disconnected from the power source, such as when the battery is disconnected or goes dead. In certain conditions, the system may display a code entry screen. If this occurs, reactivate the audio system.
Reactivating the audio system
1. Turn the ignition switch to ON *1.
2. Turn on the audio system.
3. Press and hold the audio system power button for more than two seconds.
The audio system is reactivated when the audio control unit establishes a connection with the vehicle control unit. If the control unit fails to recognize the audio unit, you must go to a dealer and have the audio unit checked.
Honda Civic Owners Manual. Security System Alarm
The security system alarm activates when the trunk, hood or doors are
forcibly
opened. The alarm does not go off if the trunk or doors are opened with the key,
remote transmitter or smart entry system*.
However, the alarm activates if a door is opened with the key and then the shift
lever
...